Admit it; you are jealous of that cute little baby. Her hair is silky soft, perfectly shiny, and does not even require a refresh after each nap. As you age, the anatomy of your hair matures (hopefully, along with your patience). To understand how products affect your hair, it is important to understand the different parts that make up the hair. In this post, we will be reviewing what each part brings to the table and how it influences your hair growth. To begin, your hair is made up of two, maybe three, parts: the cuticle, the cortex, and (sometimes) the medulla.
The cuticle is the protective barrier of the hair. Think of it like the shell on a turtle. Keratin scales develop in an overlapping pattern that surrounds the cortex. Each scale grows by the root point, with an unattached end pointing towards the tip of your hair (looks a bit like the layers of a pine cone.) These scales are somewhat dynamic and will respond to changes in pH and water absorption. They can tighten and lift away from the cortex conditionally.
If you are looking for a shampoo that will get your hair clean but not disrupt the cuticle layer consider Kinky Curly Come Clean Moisturizing Shampoo. It contains C14-16 Olefin Sulfonate, which is a great surfactant (fancy word for “cleaner”). However, this shampoo is only moderately concentrated and will not disrupt the cuticle layer so it can be used on a weekly basis.
(If you are looking for a more serious cleaner consider Malibu Un-Doo Goo Shampoo. We have more information about this shampoo at the bottom of this post.)
Every scale is made up of 5 different sections, (1) the epicuticle, (2) the A-layer, (3) the endocuticle, (4) the exocuticle, and (5) the cell membrane complex. A major difference between these sections is their cystine content. Cystine is an amino acid that contains disulfide bonds (a chemical bond that does not separate easily). Layers that are resistant to water absorption will have higher levels of cystine, which enables the protective nature of the cuticle. The A-layer, exocuticle, and epicuticle all have higher cystine levels, creating a stiff barrier that is water repellant. The endocuticle and the cell membrane complex have much less cystine and tend to absorb things like water and oil easier. When they absorb, they will expand, causing the scale to swell away from the cortex.
Because the endocuticle is less resistant, this is considered the weakest point of the cuticle and is where stretching or separation damage will happen. Most cuticle damage is caused by friction during hair maintenance when the cuticle scales are separated and delicate. Motions like scrubbing the scalp or brushing hair can show up as rough scale edges, lifting irregularities, and splitting. Make sure you’re gentle with your hair; products aren’t the only answer.
Underneath the cuticle, we find an assortment of various spindle-shaped cells bound together. These are known as macrofibrils, otherwise known as the sensitive protein core of your hair. They are important for structure and define the overall shape of your hair. The cortex is the scaffolding that keeps hair strong, defines curl patterns, and contains the pigment of the hair. There is a lot of research being put into the study of the arrangement of the macrofibrils, and how this affects hair shape. What is known is the number of disulfide bonds in the cortex dictates how elliptical the hair will be. When the cortex is cylindrical, the hair will be straighter. The more disulfide bonds there are, the more ovoid in shape the hair will be. This is what creates the curl patterns of your hair. The number of spindle-shaped cells will also change the hair width and textures, from fine to very coarse hair. The space between these spindles is the cellular membrane, which is considered the primary route of distribution of product into your hair.
Not everyone has a medulla in their hair. It is typically found in coarse or gray hairs and is thought to affect the performance of the hair dying process. Interestingly, medullated hair is slightly more difficult to color than non medullated hair because the hollow space results in less hair protein for dye to attach to and is more difficult to fully saturate with hair dye. The medulla is a liquid pocket between the macrofibrils of the cortex.
During the keratinization stage of growth, dead hair cells are essentially able to be exfoliated out. This allows these sections to naturally dry out, leaving an empty space along the axis of the hair. The medulla can be a continuous hollow space through the entire hair or can be fragmented. There are studies that suggest the function of the medulla is to contain hair lipids that will upkeep hair glossiness, but the research is not conclusive.
Though everyone has a different hair structure, proper care and maintenance of your hair is equally important to keeping your hair as youthful as a baby.
Now that you know the basics of hair anatomy, you are better prepared to choose products that are the right fit for your hair needs. Need recommendations for a shampoo? Here are two we like but each one helps you achieve different goals so be sure to pick based on your specific needs:
- Kinky Curly Come Clean Moisturizing Shampoo – Contains C14-16 Olefin Sulfonate, which is a great surfactant. However, this shampoo is only moderately concentrated and will not disrupt the cuticle layer so it can be used on a weekly basis.
- Malibu Un-Doo Goo Shampoo – This shampoo is designed to clarify using both detergents and a high pH. The high pH indicates that it will slightly raise the cuticle layer to help remove buildup. We don’t recommend using this more than once a month. Also, be sure to follow with the paired conditioner to bring the pH back to healthy range for hair. Most conditioners will do this, but I cannot report that all will. *Do not recommend for those with predominately high porosity hair*
- Alexander P. Fellows, M. T. (2020). Nanoscale Molecular Characterizaiton of Hair Cuticle Cells Using Integrated Atomic Forc Microscopy-Infrared Laser Spectroscopy. Applied Spectroscopy, 1540-1550.
- Cibele Rosana Ribeiro de Castro Lima, R. A. (2019). Heat‐damaged evaluation of virgin hair. Journal of Cosmetic Dermatology, 1885-1892.
- Duane P. Harland, R. J. (2014). Three-dimensional architecture of macrofibrils in the human scalp hair cortex. Journal of Structural Biology, 397-404.
- Faduma M. Maddar, D. P. (2019). Nanoscale Surface Charge Visualization of Human Hair. Analytical Chemistry, 4632-4639.
- Jordana Dias dos Santos, H. G. (2019). Raman Spectroscopy and electronic microscopy structural studies of Caucasian and Afro human hair. Heliyon , e01582.
- Monika Grymowicz, E. R. (2020). Hormonal Effects on Hair Follicles. International Journal of Molecular Sciences, 5342.
- Rita de Cassia Comis Wagner, P. K. (2007). Electron microscopic observations of human hair medulla. Journal of Microscopy, 54-63.
- Sandra L. Koch, M. D. (2019). Variation in human hair ultrastructure among three biogeographic populations. Journal of Structural Biology, 60-66.
- Xu Liwen, Liu Kevin X., and Senna Maryanne M. (2017) A Practical Approach to the Diagnosis and Management of Hair Loss in Children and Adolescents. Frontiers in Medicine. 4(112). doi: 10.3389/fmed.2017.00112